The increase in demand for shoes for sports and outdoor activities such as walking, running, hiking, and playing tennis, basketball and like sports has prompted many advances in shoe design to improve protection and comfort to the feet, ankles, legs, hips, etc., especially to improve cushioning, shock absorption, and stability at the heel.
Typically, the sole of the shoe and any design included in the sole is manufactured before the shoe is assembled using steel cutting dies and die-cutting machinery that create the tread design of the sole. Sole designs can also be created through injection molding, with the assembly taking place after the production of the sole. With these methods the bottommost layer of foam or rubber has the design die cut or molded into it. Once the bottom layer has been molded, or die cut and the die cut material removed, the footwear is assembled, and the bottommost layer of the sole is adhered to the rest of the footwear. Because of the cost of producing the steel cutting die or producing a mold for injection molding, these two production methods are cost-effective for creating large numbers of the same style of tread pattern but are typically not cost effective for generating a small number of shoes.